1. Field of the Invention
The present invention relates generally to a billing method in an electronic switch in a cellular network, and more particularly, to a method of billing service provided in a cellular network based on the actual time normal service is provided without interruptions.
2. Description of the Related Art
An electronic switch manages billing data for each subscriber in order to charge the subscriber for services provided to the subscriber. Billing in the electronic switch is calculated in two ways, namely, how long a line is occupied and how much data is communicated.
The former scheme is generally employed when billing using an electronic switch. In order to bill a service based on the time period provided called the service provided time period, the difference between a service start time and a service end time is calculated.
Billing in the electronic switch is a procedure of generating billing data at every call termination in a call processing block; temporarily storing and processing the billing data in a billing block; and storing the processed billing data on a billing magnetic tape or sending it to a CAMA (Centralized Automatic Message Account).
The call processing block has processing elements corresponding to call types for controlling the entire call processing and is interlocked with other blocks through a library block to facilitate implementation of inter-block operations. Basic call processing, billing, statistics, and data about operating and maintenance are defined with data representing the time periods associated with service states and other information are stored in the library block.
FIG. 1 illustrates a conventional billing procedure in which a service initiation time and a service termination time are stored and then a signal is generated for issuing a billing ticket.
First, a call processor typically an ASP (attached support processor), determines whether call has been initiated in step 111. The call initiation corresponds to a call termination request when a network calls a specific subscriber and a call origination request with which an internal subscriber calls another internal subscriber or an external subscriber through a network. Upon call initiation, the procedure continues at step 113, in which the ASP initializes a data base, which includes initialization of a service start time (st_sec and st_msec) in a call register. Here, st_sec is a count accumulated from a reference time in second units and st_msec is a count expressed in millisecond units, ranging from 0 to 999 milliseconds. If call initiation is unsuccessful, the service returns to normal operation in step 127.
In step 115, the ASP determines whether a service initiation signal has been received after a normal service set-up. A service is normally set up when a called party answers in response to the origination request or the termination request. Upon receipt of the service initiation signal, the procedure continues to step 117, in which the ASP stores the time when the call has been initiated as a service start time in seconds and milliseconds (st_sec and st_msec).
The ASP then implements a call service in step 119 and determines whether a service termination signal has been received in step 121. Upon receipt of the service termination signal, the procedure continues at step 123. If no service termination signal is received, the ASP again implements a call service in step 119.
In step 123, the ASP stores the time when the service termination signal has been received as a service end time end_sec and end_msec, and it sends billing data including the stored service start and end times to a billing processor in step 125, ending the procedure.
A disadvantage with the conventional billing method described above is that a subscriber is billed during a time period in which service is not provided to the subscriber due to a temporary service interruption or due to delayed signals being transmitted from the system to the subscriber. That is, a service charge is unfairly imposed during a “non-service time period”, requiring the subscriber to pay excessive service charges.